Porth's Essentials of Pathophysiology, 4e

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Integumentary Function

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Treatment of more severe cases usually requires oral antifungal therapy, such as terbenafine, administered for several months. 8 All of the oral agents require careful monitoring for side effects. A nail lacquer con- taining the antifungal agent ciclopirox is available for use in the topical management of mild to moderate infections of the fingernails and toenails caused by T. rubrum . A new nail may require 3 to 12 months to grow. Thus, people being treated with antifungal agents need to be reminded that the resolution of the infection requires 4 to 6 months for fingernails and longer for toenails. Dermatophytid Reaction. A secondary skin eruption may occur in persons allergic to the fungus respon- sible for the dermatophytosis. This dermatophytid or allergic reaction may occur during an acute episode of a fungal infection. The most common reaction occurs on the hands in response to tinea pedis. The lesions are vesicles with erythema extending over the palms and fingers, sometimes extending to other areas (Fig. 46-5). Less commonly, papules or vesicles erupt on the trunk or extremities. These eruptions may resemble tinea corporis. Lesions may become excoriated and infected with bacteria. Treatment is directed at the primary site of infection. The intradermal reaction resolves in most cases without intervention if the pri- mary site is cleared. Candidal Infections. Candidiasis (moniliasis) is a fun- gal infection caused by C. albicans . This yeastlike fun- gus is a normal inhabitant of the gastrointestinal tract, mouth, and vagina (see Chapter 41). The skin prob- lems result from the release of irritating toxins on the skin surface. C. albicans is almost always found only on the surface of the skin; it rarely penetrates deeper. Some persons are predisposed to candidal infections by

conditions such as diabetes mellitus, antibiotic therapy, pregnancy, oral contraceptive use, poor nutrition, and immunosuppressive diseases. 9 Oral candidiasis may be the first sign of infection with human immunodeficiency virus (HIV). Candida albicans thrives on warm, moist, intertrigi- nous areas (i.e., between folds or adjacent surfaces) of the body. The rash is red with well-defined borders. Patches erode the epidermis, and there is scaling. Mild to severe itching and burning often accompany the infection. Severe forms of infection may involve pus- tules or vesiculopustules as well as maculopapular satellite lesions found outside the clearly demarcated borders of the candidal infection. Satellite lesions often are diagnostic of diaper rash complicated by Candida . The appearance of candidal infections varies according to the site (see Chapter 41 for a discussion of vaginal candidiasis). Diagnosis usually is based on microscopic examina- tion of skin or mucous membrane scrapings placed in a KOH solution. Treatment measures vary according to the location. Preventive measures such as wearing rub- ber gloves are encouraged for persons with infections of the hands. Intertriginous areas often are separated with clean cotton cloth and allowed to air dry as a means of decreasing the macerating effects of heat and moisture. Topical and oral antifungal agents, such as clotrima- zole, econazole, ketoconazole, and miconazole, are used in treatment depending on the site and extent of involvement. Bacterial Infections Bacteria are considered normal flora of the skin. Most bacteria are not pathogenic, but when pathogenic bac- teria invade the skin, superficial or systemic infections may develop. Bacterial skin infections are commonly classified as primary or secondary. Primary infections are superficial skin infections such as impetigo. Secondary infections consist of deeper cutaneous infections, such as infected ulcers. Diagnosis usually is based on cultures taken from the infected site. Treatment methods include antibiotic therapy and measures to promote comfort and prevent the spread of infection. Impetigo. Impetigo is a common, superficial bacterial infection caused by staphylococci, group A β -hemolytic streptococci, or both. 10 It is common among infants and young children, although older children and adults occasionally contract the disease. Impetigo initially appears as a small vesicle or pustule or as a large bulla on the face or elsewhere on the body. As the primary lesion ruptures, it leaves a denuded area that discharges a honey-colored serous liquid that dries as a honey-colored crust with a “stuck-on” appearance (Fig. 46-6). New vesicles erupt within hours. Pruritus often accompanies the lesions, and skin excoriations that result from scratching multiply the infection sites. Although a very low risk, a possible complication of untreated streptococcal impetigo is poststreptococcal glomerulonephritis (see Chapter 25). Topical mupirocin

FIGURE 46-5. Dermatophytid or id reaction on the fingers due to a tinea infection. An id immunologic reaction, also known as autoeczematization, is an itchy, vesicular rash produced in response to an intense inflammatory process that can be located in another region of the body. (From the Centers for Disease Control and Prevention Public Health Image Library. No. 4805.)